Indicating system



Oct. 14, 1952 R FQQTE ET 1 2,614,160

INDICATING SYSTEM 2 SHEETS-SHEET 1 Filed July 28, 1951 LL FAULT FINDER 4 RESET SWTCH UNDER VOLTAGE 2C: 20 RESET Inventors:

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Oct. 14, 1952 R FOOTE T AL 2,614,160

INDICATING SYSTEM Filed July 28 1951 2 SHEETS--SHEET 2 Fig.2.

FAULT FINDER RESET Invemtovs: LEBWT'IETWCLE 1 FOObc'B-i Willianw LO. GYGViFS *each" corresponding to a Patented Oct. 14, 1952 PATENT OFFICE.

NDICATING SYSTEM "Lawrence. Bel-Footie and William v L. o. Graves, Schenectady, N. Y., assignors, toy G eneral Electric Company, a corporationoflNew York jApplication'July 28, 1951, seriai-Najzsaisi Claims.

'Th-is invention relates to indicating-"systems, more particularly tov systems for operating condition of any one of a plurality of -'switche's having their conta'cts' connected-in indicating the series i'elation'shipon a control circuit; 1'. e. indicating whether 'each -s'witch is open or closed and it has for an object the-provision of a simple,

-rellable and-improvedsystem of this character.

Amore-specific-object of the inventionis the -provis'ion; of am'emorytype fault :finding system I for usewith industrialdrives which have a plur alityot protective interlocks v '14 31 carrying the" invention int-o effect in' one -;f orm--thereof thecontacts of a plurality of switching devicesware'connectd in series relations'hip with each other across a pair or direct voltage supply conductors; and a plurality of electric valves used' as glow-lamps are provided, different/one of the switches. Each of these valves contains within itsienvelope',-ananode-a cathode, a control e1ec-' f trode and" an 'ionizable medium: The cathodes tothenegative supply conductor; and az'sepa'rate connection is; provided from leach anode to the negative-"contact of; a corre- "sponding switching device- A fault finder reset v swit'ch' p'rovides for "completion of thef'conne'ction .of the'oontrol electrodes Of all these electric "valves to the positive supply conductor to estab- :lishionizati'on and'ic'onduction, and thereby effect a a glow illumination thereof if the contacts of all "of the'switch'ing devices arefclosed Thus; the i-llumination'iot all of the .valves is an indication that 'all'of'the contacts-are closed.

The opening of anvone ojf'th-e switching devices effects deionization and extinguishment of all of the electric valves having'their anode connections to'the positive supply conductor completed through the contacts of such switching device, and the remaining valves whose anode connections to the positive supply conductor do not pass through the contacts of such switching device remain illuminated. A knowledge of the r groupings of the electric valves whose anodec-ircuits are completed through each'switching de-' vice enables the operator by observation of illuminat-ed and darkvalves, to determine which switch opened its contacts. open switch contacts are promptly reclosed the,

7 Even though the extinguished valves remain extinguished and the unextinguished valves remain illuminated. In

other words, the indicating system has a memory. After making a recorder the identity of the switch which causedtt he ;inter-ruption, the

indicatingsystem i m'ay'cb'e reset i'sby tclo'sing the fault finder reset switch. g; Ina .modific-atiomczt-hei electric 'valves. are all extinguished "wh-enlallof the switch contactsiare 5 closed. The o-pening of-any: onewofatheiswitchring devices interrupts; the anode 1 connectionaof all the. valves .whichiare completed through such contact when closed;Arrelayzresponds.Ito :the opening of any of l. the switching ldevices-ztov-conl0 s nect thelcontrol electrodes :of. 531111; .of ;;the;;valves to the positive. supply;;conductors.g :Theigmup; of a valves whose-anode:gconnections-oweitezinteltrupted vremaindarkcanduthe group whoscsanodes 'remaininonnected .toxthe; positive: supplyicondiictor .fiIB'illllIIllIlfitBdlj This. modification alSDzfhns a mem-ory. feature; 1.- e.zt e;-illumina-,ted"valyes remain illuminated untilflapiaultz.: finderzre 1 switch is opened to. interrupt the anodecathode circuit of allof the-.va'lves; if" 1:. no ,For a better and :moreoomdfite understan ing of the invention, reference should now be had to t e following specification an s-to: the acco panying -dr wi.ng-of which Fi -:11 is assimn d Hgrammatical illustration of; anembodiment of the invention andMF aiN :i-s ans/1 .11pm; d a ra maticalsillustration, of a modification. Rei rri w ow .w to the:;;drawins;mlura i yw switchi dev ces L. .2,,. Sma t or sl with interlock contacts la, 2a, 3a, 4a, andfiu s respec ive y. each; o whichzlis o q edc cn t 7 operat n cc d t o cwh ch it. p s has a vi .mal operat n lva uec 'lih se. with g evic may lbereither .te ecvtr maenetiqally chem Yd; or ;,mec anica lyoperated. ilor;exam-pl ,pth tc 35.. inc devices 1,: L1 and .5 ar illu ate troma n t w h s. a t e, :trated as acc trc uealsw tc Th e. conta ts are (1. 0a t n h p. w a h ot er. l wh c extend ro ithey p9 1 e n ly V tor B;to the. negative supply conductor 6o.

';op. ra in ...coi1 11a of. .a celec roma n ti .1 .in dev erl a d the normall enconta t 8 a eset swit h n d v ce t h :l r eteb :ofthe;nush.button tyne are 15 u eii cri relati ns p; .a this contr. A 1. is lo ed w ha l ngdesqen ac s lel with the contacts of the reset switch g Di c volta .oi ui ab e 1p 50. to thei up co duc o an .i a lfi sou c n t shown: Fortun r os .oiipr-or s ne a i a n1 n-op n 0i n ioneyo fthelswi che l 5 c u v nd t in n su diqe i nr te btlto va p 9it ;in ialjrco iiipp ea plurellt j "locks.

electric valves 9, It, II, I2 and I3, used as glow lamps, are provided which correspond to the switching devices I, 2, 3, 4, and 5 respectively. Although these electric valve glow lamps may be of any suitable type, they are preferably OA-G gas triodes which are generally referred to as cold cathode thyratrons. The electric valve 9 contains within its envelope an anode 9a, a cold cathode Sb, a control electrode 90 which is usually referred to as a starting anode, and an ionizable medium such, for example, as argon, mercury vapor, or neon. The electric valves M, H, I2, and I3 are identical with electric valve e.

As shown, the cathodes 912, I02), IIb, I22), and I3b are directly connected to the negative supply conductor 6a. A conductor I4 connects the anode 9a of electric valve 9 to the negative terminal of the pair of switching device contacts Ia. When the contacts I a are closed, the anode 9a is connected through these contacts to the positive supply conductor 6. Similarly, conductors I5, IS, IT, and I8 connect the anodes Illa, Ila, I2a, and I30, to the negative terminals of contacts 2a, 3a, 4a, and 5a respectively. When all of the contacts Ia, 2a, 3a, 4a, and 5a are closed, all of the anodes 9a, Illa, Ila, I2a, and I3a are connected to the positive supply conductor 6. The connection of each anode to the positive supply conductor passes through all of the series connected contacts between the negative contact to which it is connected and the positive supply conductor 6. Consequently if any selected pair of contacts is open, all of the electric valves having anode connections through such contacts (when closed) to the positive supply conductor are deionized and the illumination thereof is extinguished.

The anode-cathode circuit of electric valve I9 which is identical with lamps 9-I3 inclusive is connected directly across the supply conductors 6 and So without passing through any switch contacts. It furnishes an indication of voltage across the control voltage supply conductors 6 and 6a.

Current limiting resistors 29, 2I, 22, 23, 24, and

' are connected in the anode circuits of electric valves I9, 9, II], II, I2, and I3 respectively. The resistance of each of these resistors is of the order of 3,500 ohms. However, this value is not critical.

For the purpose of reestablishing ionization and illumination in each electric valve, the control electrodes I90, 9c, I 00, Ho, I20, and I are connected through the normally open contacts of a fault finder reset switch 26 to the positive supply conductor 6. The reset switch is preferably a momentary contact type push button switch. A protective resistor 2'! which may suitably have a resistance of 3,500 ohms is included in the connection between the switch and the negative supply conductor 6a. Suitable current limiting resistors 28, 29, 30, 3|, 32, and 33 are included in the connections between the switch 26 and the control electrodes I90, 90, Ilic, IIc, I2c,

and I3c respectively. These resistors have a fairly high resistance, e. g. one-fourth megohm.

For the purpose of illustration of the application of the indicating system to a typical industrial drive the switching devices I, 2, 3, 4, and 5 may be considered to be the overvoltage, overcurrent, overspeed, field loss and motor starter protective interlock switches of a steel rolling mill drive. A typical steel rolling mill control may have as many as sixty such protective inter- The relay 1 may be considered to be the undervoltage relay which provides the system undervoltage protection. In a steel mill application it operates as a master protective interlock and the mill cannot be operated unless it is energized.

With the foregoing understanding of the elements and their organization, the operation of the complete fault finder and indicating system will readily be understood from the following detailed description.

It is assumed that all the protective interlock contacts I a, 2a, 3a, 4a, and 5a are closed. The external main anode-cathode circuits of each electric valve will be completed through all of the interlock contacts between the anode and the positive supply conductor. The electric valves, however, will remain dark since completion of the anode-cathode circuit does not result in sufficient ionization to establish conduction.

The undervoltage reset push button 8 is then depressed to close its contacts to complete an energizing circuit for the operating coil 1a of the master undervoltage relay 1. In response to energization this relay closes its interlock contacts Ib to complete a sealing-in circuit around the contacts of the undervoltage reset switch 8 which may now be released.

To illuminate all the electric valves to furnish an indication that all protective interlocks are closed, the fault finder reset switch 26 is momentarily depressed to connect the starting anodes of all the electric valves to the positive supply conductor 6. As a result, ionization is established in all electric valves and conduction is initiated between the cathodes and main discharge supporting anodes of the valves causing them all to become illuminated, which condition indicates that all protective interlock contacts are closed.

If during the operation of the mill there should be a departure from a safe value of any mill operating condition protected against by one of the protective interlock switches, such relay will open its contacts. For example, a momentary overload on the mill will cause the overcurrent relay 2 to open its contacts 2a momentarily. Upon termination of the momentary overload, the overcurrent relay will reclose its contacts.

The momentary opening of contacts 2a will interrupt the energizing circuit of the undervoltage relay 8 which will drop out and shut down the mill. Also, the four electric valves I0, II, I2, and I3 whose anode circuits are normally completed through contacts 2a will be deionized and extinguished, and will remain extinguished even though the anode voltage is promptly restored by reclosure of the contacts 2a.

The operator may restart the mill immediately by momentarily depressing the undervoltage re- Set push button switch 8. After the mill has been restarted, the operator by observing the electric valves determines which interlock caused the interruption. For example, if electric valves 9-I3 inclusive are extinguished, the operator knows that interlock contacts Ia opened since contacts Ia are the only contacts through which the anodecathode circuits of all five lectric valves 9-I3 inclusive pass. Similarly, if electric valves I0, II, I2 and I3 are extinguished, which is the condition assumed for the purpose of illustration, he knows that interlock contacts 2a opened, since these contacts are the only contacts other than contacts Ia through which pass the anode-cathode circuits of these valves. Since valve 9 is still illuminated, the operator knows that contacts Ia are closed, Thus, the electric valves have acted as a-- rnemory} device toprovideran indication of after-reclosurer -Thefourextinguished electric: A valves. may.

' again be illuminated by momentarilyv depressing the fault finder reset push button switch.

--- -ln the modification illustrated in Fig. 1, the

' indicating valves are i continuously conducting -and--illuminated during normal conditionsxi. e. when all protective interlock contacts l 5. inclusive are closed. This shortens the useful lives of the electric-valves. i a .1

A modified indicating system in which .the valves are extinguished during the normal conxii-tion and'illuminatedin selective groupings durg-ing-an'abnormal-operatingcondition is illustrated in Fig. 2. -This modification is generally. similar tolthe modification of Fig. land identical parts both figures-are represented by the samereference characterg Inthe modification. of Fig. 2

. .indicates that/interlock. contacts M7512 inclusive are. closed.

If contact 3a, for example, should open inrevsponse to an abnormal value of an operating condition, it disconnects the anodes Ha, Na, and 13a from the positive supply conductor and interrupts the energizing circuit of undervoltage relay 1. Relay 1 drops out and closes its normally closed contacts 1c to complete a charging circuit forthecapacitor 35 to the positivesupplyconductor 6. Since the capacitor cannot charge instantaneously, the voltage of the common control a. electrode terminal becomes substantially the voltage of the positive supply conductor 6 Consequently, the valves whose anodes are still con- I nected to thepositive conductor, 1. e. valves I3, 119, and-i are illuminated and the valves l I, 12, and I3 whose anodes were disconnected from the positive supply conductor by the opening or contacts 3a remain dark. Since contacts lc, 2a, and

'- 3a are'the" onlycontacts through which anodes lia lza, and 13a are connectedto the positive certain changes have been incorporated inthe v supply conductor ii the operator knows that confiring circuit', i..'e. the control electrode :circuit in order to provide for an indication ofxthe normal condition 'byextinguishment of the valves.

In this modification, a resistor 34, pair of -auxiliary normally closed contacts 1c of the undervoltage relay 1 and a capacitor are connested in series relationship between the positive supply conductor 6 and'the common control electrode terminal 33a.

A discharge resistor 36 is connected'in parallel with capacitor 35.

. Although th values of resistors 34 and 38 and capacitor 35 are-not critical, resistor 34 may have 3,000'ohms, resistor 36 aresistance of 1 megohm' and capacitor 35 may have a [capacity or .01 mfd. 1 i

' The fault finder reset switch 31 is illustrated as a normally closed push button type switch "connected in a common conductor 38 between the cathodes of all of the valves and the negative supplyconductor. 'A test switch 40 which is illustrated as a push button type switch having normally open contacts, is connected in parallel with capacitor 35.

The operation'is as'follows: Assumingthat all interlock contacts Iii-5a inclusive are closed, and that the undervoltage relay 1 is deenergized and dropped out, the normally closed contacts 1c of the undervoltage relay 1 are closed. Capacitor 35 is charged to the full lin voltage across supply. conductors 6 and Ba so that the voltage applied tothe control electrodes is substantially the voltage of the negative supply conductor 6a. Consequently, the valves are deionized Jand extinguished. The test switch 4 0 may be momentarily closed to connect'the control electrodes of all valves to the positive starting conductor. Each valve which is in goodoperating condition will be ionized and illuminated. A defective valve will remain dark and must be replaced.

Following the testing of the valves, the fault 'finder', reset switch is depressed to interrupt the "common", cathode circuit thereby to extinguish all f valves. The undervoltage reset switch 8 is then closed to' complete an energizing circuit for the operatingcoil or 'theundervoltage relay 1'. Re-

s'ponsi'vely to energization, relay 1 picks 'up and closes its normally open contacts lb to complete a sealing-in circuit and opens its normally closed contacts 10 to interrupt the charging circuit of capacitor 35 which discharges through resistor tacts 3a must be open because the illumination of valves 9 and Ill informs him that contacts In a and 2a are closed.

Once, conduction has been initiated, the valves remain conducting until their anode-cathode circuits are interrupted.- Similarly, the darkened valves remain extinguished after reclosure of the open interlock contacts because ionization sufiicient to initiate conduction is produced only during-the brief fraction of-a second following closing' of contacts 10 in which the capacitor 35 is sufiiciently discharged to elevate the voltage of dication of the momentary opening of one of the interlock contacts and to retain such indication after reclosure.

-After the necessary'corrective measures have beentaken, the indicating system may be reset,

--i. e. the illuminated valves may be extinguished by opening the fault finder reset switch 31.

Although in accordance with the provisions of the patent statutes, this inventionis described as embodied in concrete form and the principle of the inventionhas been explained together with --the bestiorm in which it is now contemplated,

applying that principle, it will be understood that the-apparatus shown and described is merely illustrative and that the invention is not limited thereto since alterations and modifications will readily suggest themselves to persons skilled in the art without departing from the true spirit of i the invention or from the scope of the annexed claims. a I

What we claim as new and desire to secure by 7 Letters Patent of the United States is:

1. An indicating system comprising in com- "bination first and second supply conductors, a control circuit connected across said supply conductors comprising a plurality of switch contacts connected in series relationship, a plurality of electric valves each corresponding to a different one of said contacts and each having first and second main discharge supporting electrodes, 2.

0nd. The switch 8 may now be released. All

..,,;valves.3I3 inclusive are dark and this condition control electrode and an ionizable medium, a source of ignition voltage for said control electrodes, a common electrical connection. from said control electrodes to one terminal of said source, a second common connection from said first main discharge supporting electrodes to, said first supply conductor and a plurality. of separate electrical connections each extending from the corresponding terminal of a different one of said contacts to the second main discharge supporting electrode of the corresponding electric valve to produce in response to opening of one of said contacts a pattern of illumination in which each of said valves having its main electrode circuit remaining completed is illuminated and each of said valves having its main electrode circuit interrupted is extinguished, and a reset switching device included in one of said common connections for restoring the initial condition of illumination of said valves existing prior to said opening of said switch contacts.

2. An indicating system comprising in combination first and second supply conductors, a control circuit connected across said supply conductors comprising a plurality of switch contacts connected in series relationship, a plurality of electric valves each corresponding to a different one of said contacts and each having a first main discharge supporting electrode connected to said first supply conductor, a control electrode, a second main discharge supporting electrode and an ionizable medium, a source of igthe corresponding terminal of a different one of said contacts to the second main discharge supporting electrode of the corresponding electric valve to produce in response to opening of one of said contacts a pattern of illumination in which each of said valves having its main electrode circuit remaining completed is illuminated and each of said valves having its main electrode circuit interrupted is extinguished, and a reset switching device for restoring the initial condition of illumination of said valves existing prior to said opening of said switch contacts.

3. An indicating system comprising in combination first and second supply conductors, a control circuit connected across said supply conductors comprising a plurality of switch contacts connected in series relationship, a plurality of electric valves each corresponding to a different one of said contacts and each having a first main discharge supporting electrode connected to said first supply conductor, a control electrode, a second main discharge supporting electrod and an ionizable medium, an electrical connection from each of said control electrodes to one of said supply conductors and a plurality of separate electrical connections each extending from the corresponding terminal of a different one of said contacts to the second main discharge supporting electrode of the corresponding electric valve to produce in response to opening of one of said contacts a pattern of illumination in which each of said valves having its said second main discharge supporting electrode remaining connected to said second supply conductor is illuminated and each of said valves having its said second main discharge supporting electrode disconnected from said second supply conductor is extinguished, and a reset switching device for restoring the initial condition of illumination of said valves existing prior to said opening of said switch contacts.

4. An indicating system comprising in combination first and second supply conductors, a control circuit connected across said supply conductors comprising a plurality of switch contacts connected in series relationship, a plurality of electric valves each corresponding to a different one of said contacts and each having first and second main discharge supporting electrodes, a control electrode and an ionizable medium, a common connection from said control electrodes to one of said supply conductors, a second common connection from said first main discharge supporting electrode to said first supply conductor and a plurality of separate electrical connections each extending from the correspondin terminal of a diiierent one of said contacts to the second main discharge supporting electrode of the corresponding electric valve to produce in response to opening of one of said contacts a pat tern of illumination in which all of said valves having a second main discharge supporting electrode remaining connected to said second supply conductor are illuminated and all of said valves having a second main discharge supporting electrode disconnected from said second supply conductor are extinguished, and a reset switching device included in one of said common connections for restoring the initial condition of illumination of said valves existing prior to said opening of said switch contacts.

5. An indicating system comprising in combination, positive and negative supply conductors, a control circuit connected across said supply conductors comprising a plurality of switch contacts connected in series relationship, a plurality of electric valves, each corresponding to a. difierent one of said switch contacts and each having a cathode connected to said negative supply conductor, a control electrode, an anode and an ionizable medium, an electrical connection from each of said control electrodes to said positive supply conductor and a plurality of separate electrical connections each extending from the negative terminal of a different one of said switch contact to the anode of the corresponding electric valve to effect in response to opening of one of said contacts a pattern of illumination in which all of said valves having an anode remaining connected to said positive supply conductor are illuminated and all of said valves having an anode disconnected from said positive supply conductor are extinguished, and a reset switching device for restoring the initial condition of illumination of said valves existing prior to said openin of said switch contacts.

6. An indicating system comprising in comloination, positive and negative supply conductors, a control circuit connected across said supply conductors comprising a plurality of switch contacts connected in series relationship, a plurality of electric valves, each corresponding to a dinerent one of said switchcontacts and each having a cathode, a control electrode, an anode and an ionizable medium, a common connection from said cathodes to said negative supply conductor, a second common connection from said control electrode to said positive supply conductor, and a plurality of separate electrical connections each extending from the negative terminal of a difierent one of said switch contacts to the anode of the corresponding electric valve to produce in response to opening of one of said contacts a pattern of illumination in which all of said valves having an anode remaining connected to said positive supply conductor are illuminated and all of said valves having an anode disconnected from said positive supply conductor are extinguished, and a reset switching device included in one of said common connections for restoring the initial condition of illumination of said valve existing prior to said opening of said switch contacts.

7. An indicating system comprising in combination, positive and negative supply conductors, a control circuit connected across said supply conductors comprising a plurality of switch interlock contacts connected in series relationship, a corresponding plurality of electric valves each containing a cathode connected to said negative supply conductor, a control electrode, an anode and an ionizable medium, a corresponding plurality of connections, each extending from the negative terminal of one of said switch interlock contacts to the anode of a corresponding one of said electric valves, to effect in response to opening of one of said contacts the deionization and extinguishment of all of said valves having an anode connected to a terminal more negative than the po itive terminal of said open contact, a connection from each of said control electrodes to said positive supply conductor and a reset switching device included in said last mentioned connections for effecting ionization and initiating conduction in all of said extinguished electric valves in response to momentary closure of said reset switching device after reclosure of said open interlock contact.

8. An indicating system comprising in combination, a plurality of switching devices each having a pair of contacts, positive and negative :5

supply conductors, a control circuit connected across said supply conductors comprising said switch contacts connected in series relationship, a plurality of electric valves each corresponding to a difierent one of said switching devices and each containing a cathode connected to said negative supply conductor, a control electrode, an anode and an ionizable medium, a corresponding plurality of connections each extending from a different one of said anodes to the negative contact of a corresponding one of said switching devices to effect in response to opening of a selected pair of said contacts deionization and extinguishment of those of said electric valves having anode connections to said positive conductor completed by said selected contacts when closed, a separate connection from each of said control electrodes to said positive supply conductor and a reset switching device included in said last mentioned connections for effecting ionization and restoring conduction in said extinguished electric valves in response to momentary closure of said reset switching device after reclosure of said selected contacts.

9. An indicating system comprising in combination, positive and negative supply conductors, a plurality of switching devices each having a pair of contacts, a control circuit connected across said supply conductors and comprising said contacts connected in series relationship, a plurality of electric valves each corresponding to a different one of said switchin devices and each containing a cathode connected to said negative supply conductor, a control electrode, and anode and an ionizable medium, a plurality of separate electrical connections each extending from a different one of said anodes to the negative contact or" a corresponding one of said switching devices, each of said pairs of contacts in opening serving to deionize and extinguish all of said lamps having anode connections to said positive conductor completed thereby, connections from said control electrodes to said positive supply conductor, a reset switch included in said control electrode connections for reestablishing ionization and conduction in said extinguished valves in response to momentary closure of said reset switch after reclosure of said opened contacts.

10. An indicating system comprising in combination, positive and negative supply conductors, a plurality of switching devices each having a pair of contacts, an undervoltage relay having an operating coil, an undervoltage reset switch having normally open contacts, a control circuit connected across said supply conductors and comprising said switching device contacts, said normally open contacts and said operating coil connected in series relationship, a pair of sealing-in contacts on said relay short-circuiting said normally open contacts in the picked-up position of said relay, a plurality of electric valves each corresponding to a different one of said switching devices and each containing a cathode connected to said negative supply conductor, a contro1 electrode, an anode and an ionizable medium, a plurality of separate electrical connections each extending from a diiierent one of said anodes to the negative contact of a corresponding one of said switching devices, each of said pairs of switching device contacts in opening effecting deionization and extinguishment of all of said valves having anode connections to said positive conductor completed thereby, connections from said control electrodes to said positive supply conductor, a second reset switch included in said control electrode connections for reestablishing ionization and conduction in said extinguished valves in response to momentary closure of said second reset switch after reclosure of said opened contacts.

LAWRENCE R. FOOTE. WILLIAM L. O. GRAVES.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

